This invention relates broadly to an assembly for detecting defects in articles of manufacture and more specifically relates to the apparatus for automatically detecting defects in glassware.
It is oftentimes necessary to monitor articles of manufacture to assure that desired product quality levels are achieved. It is readily apparent, for example, to those having knowledge in the manufacture of glassware that finished glassware products may not be perfectly formed and may therefore in some cases not be entirely suitable for the use intended. By providing monitoring or inspection devices to eliminate those articles of manufacture which are not entirely suitable and therefore considered defective for a specific use, product quality can be enhanced. In glassware "spikes" which are sharp glass projections formed in glassware and "birdswings" which are found generally in bottles and which comprise thin pieces of glass extending across opposite inner walls thereof are examples of items for which glassware is often inspected and glassware rejected if present. Obviously, monitoring or inspection systems and a degree of reliability inherent in any such system for monitoring unwanted characteristics in finished glassware products or other such articles of manufacture are often important in achieving quality of the product.
Heretofore monitoring systems for detecting defects in glassware have taken various forms ranging from, for example, mere visual inspection utilized in the slow production of glassware to complex electronic detection systems utilized in the more rapid production of glassware. One such inspection apparatus is disclosed in application for patents Ser. No. 520,227, filed Nov. 1, 1974, and entitled "Method and Apparatus for Video Inspection of Articles of Manufacture." In that application a light source is positioned adjacent one side of and optically spaced from an article to be inspected. A video camera is positioned on the opposite side of the article from the diffused light source and scans the illuminated article in order to produce a video signal indicative of the difference in the refraction characteristics of the article to thereby indicate the presence or absence of defects in the glassware sample. Circuitry is disclosed for discriminating between true defects and lettering, mold marks, and coloring normally associated with the article. In the event there is a defect, an electrical processing circuit connected to the video camera and responsive to the video signal is provided for actuating a glassware rejection mechanism. Circuit means are also disclosed for inspecting round objects, such as the bottoms of round jars or glasses.
As an example of an early electronic inspection device, Fedorchak disclosed in U.S. Pat. No. 2,649,500 a glass inspection apparatus wherein ultraviolet light was directed into the inside of a bottle. The ultraviolet light was reflected out of the bottle onto a mosaic which was in turn scanned by a cathode-ray tube. The cathode-ray tube scanned the mosaic in a spiral manner to thereby provide indication when a flaw, such as a sharp projection, occurred in the bottle. This apparatus had the drawback in that a lamp had to be positioned such that light could be directed into the inside of the bottle so that the light would be reflected therefrom. This prohibited rapid assembly line inspecting of bottles. In addition, no means were taken into account for the change in reflected ultraviolet light due to the corners of the glass jar and for other normal variances in the contour of the bottle caused by, for example, seams and lettering.
A more recent development was disclosed by Gambrell et al in the U.S. Pat. No. 3,379,829 wherein a fault detection apparatus was disclosed wherein normal pertubations in the glassware were not detected because a mask corresponding to the shape of the inspected article of manufacture provided blanking signals when normally encountered pertubations on the surface were scanned by an electronic beam. Such an arrangement, however, requires that the mask be appropriately aligned with the article being inspected and eliminates the possibility of checking flaws positioned between the masked portion of the article and the source of radiation which is detected.
Richards disclosed in U.S. Pat. No. 2,798,605 an electronic inspection apparatus for detecting foreign matter in bottles. In the Richards' invention, bottles are passed along a conveyor line and are passed in front of the optical system of a television camera. As each object passes in front of the camera, a light flash of short duration is provided to thereby illuminate the object and cause an image to be transmitted to the mosaic of the television camera tube. The mosaic is scanned by the cathode-ray gun of the camera tube which provides an output signal that indicates appreciable discontinuity in the video signal from its average level. However, this invention requires a rather complex "herringbone" sweep action in order for the inspection apparatus to distinguish between the sides of the bottle and true defects. Further, two transverse views are required of each bottle in order to detect flaws along the vertical length of the bottle, thereby requiring two separate camera systems, thus, while Richards was an improvement in the art, the method and apparatus required for inspecting the bottles remained quite complex.
While the above-referenced patents disclose various methods and apparatus for detecting imperfections in glassware, if the defect were in a position near the edge or outside portion of the container as viewed by the television camera, the defect would not be detected. While some systems are available wherein the bottle is rotated during the inspection cycle, no system is known to the applicant hereof wherein the glassware is inspected in such a manner that any defect within the area of inspection is certain to be determined.
Accordingly, it is an object of the present invention to provide a new and improved method and apparatus for monitoring and detecting defects in articles of manufacture such as glassware which is more dependable and accurate than those found in the prior art.
Another object of the present invention is to provide a new and improved apparatus for electronically monitoring detecting defects in glassware without stopping the glassware during the inspection cycle and without rotating the glassware during the inspection cycle.